Silicon carbide is considered a material for next-generation semiconductor devices. Silicon carbide has better physical properties than silicon in that its band gap is 3 times larger, its breakdown electric field intensity is about 10 times higher, and its thermal conductivity is about 3 times higher. When these characteristics are utilized, for example, metal oxide semiconductor field effect transistors (MOSFETs) capable of operating at higher breakdown voltage, at lower loss, and at higher temperature can be realized.
Vertical MOSFETs using silicon carbide have a pn junction diode as a body diode. For example, MOSFETs can be used as switching elements connected to inductive loads. In this case, even when the MOSFETs are nominally turned off, reflux currents can flow through the body diodes.
However, when reflux currents flow through the body diodes, stacking faults grow in silicon carbide layers due to charge carrier recombination, and thus there is a problem that on-state resistance of MOSFETs subsequently increases. The increase in the on-state resistance of MOSFETs results in a reduction in long-term reliability of MOSFETs.